Nowadays, national and regional exchanges have become increasingly frequent, invasive species cause a certain pressure on indigenous species, brining about a certain negative impact on ecology in some areas. Some fishes in a certain area are classified as the invasive species that shall be seemed to be cleared. The most typical example occurred in the United States and Europe, such as cyprinids such as carp has led to a larger ecological problem, resulting in declining some species population, and even endangering some rare species. Carp has been defined as the invasive species by legislation in many states of the United States, so as to allow clearing its existing individual through a variety of methods as well as avoiding the spread between the waters. It is more difficult to completely remove the existing individual of the invasive fish that mainly because there is extensive area of water areas, such as natural rivers and lakes, more shelters, individual fish moves more agile, fish swims among different areas and it is difficult to control for human beings, etc. The United States has found some ways of clearing invasive fish, such as artificial fishing, electric shock, calling for fishing, increase in invasive fish consumption, and setting of gate dams and obstacles, etc. among different water areas. However, various methods have certain limitations, such as high labor intensity and low efficiency, etc. Various methods conducing to clearing the invasive fish remain further study.
Currently, more commonly used method for clearing the invasive fish focuses on adult fish and juvenile fish. Reports from the perspective of clearing the invasive fish in terms of the fertilized eggs are still less. Some fish species such as carp have a characteristic that its eggs are of various eggs and have stronger viscosity. Although the carp can still spawn naturally in running water or still water, attachments shall be required finding so that the fertilized eggs can be adhere thereto. By the use of the characteristics that a variety of fish including carp spawns viscous eggs and needs the attachments, it is discovered that the attachments can be artificially set for eggs and the spawning rate of these fish can be raised. These artificial set attachments for eggs are called as the fish nests. The materials for preparing the fish nest just only is non-toxic, soft and slender, has more beards and is easily dispersed in water but is difficulty corrosive. Common fish nest includes fish nests made of willow roots, water hyacinth, and silk screen, etc. The root part of the fish nest is suspended in water so as to attract carps to spawn in the fish nest during the breeding season. Fish nest is a method that is discovered by people taking advantage of spawning characteristics of the fish to improve the breeding success rate of the fish. It is worth of thinking deeply in reverse thinking, i.e., clearing the invasive fish eggs by the use of the viscous eggs spawned by the fish.
Electric shock is commonly used method for catching or controlling the adult fish or juvenile fish. The commonly used method is electric fishing, in addition to low voltage anesthesia fish, etc. Fertilized eggs are at one of the most vulnerable periods of their life cycle, so that the low voltage electricity relatively safe to the human beings can kill the fertilized eggs. A method for killing and wounding the fertilized eggs of the invasive fishes can be produced by the characteristics that the fertilized eggs adhere to the attachments and can be killed by the low voltage electricity. Thus it is necessary to invent a device for killing and wounding the viscous eggs.